While you were doing whatever you were doing on Monday, a 200 foot wide asteroid passed within 40,000 miles of our little planet. The asteroid, which was only discovered on Friday, was about the size of the asteroid that destroyed the forestin Tunguska, Siberia about a century ago. Experts say an impact would have caused the equivalent of a large nuclear explosion.

The asteroid, named 2009 DD45, is likely to be drawn in by earth's gravity...which could mean return visits.